Investigating associations between fluvial style and the characteristics and distribution of geomorphic units in non-perennial rivers

Abstract

Although non-perennial rivers are the most dominant river type in arid and semi-arid areas, far outnumbering perennial rivers, recent reviews have shown that the knowledge base supporting non-perennial river research is still in its infancy. This is a cause for concern as non-perennial rivers are increasing in number due to climate and other environmental change, and over-exploitation of catchment water resources. Thus more research is needed to improve decision support in the management of non-perennial systems. This thesis examines key geomorphic units found in non-perennial reaches with contrasting fluvial styles in the Touws and Prins Rivers, semi-arid Little Karoo, Western Cape. The study analyses the different types of bar located within these characterised fluvial styles, as the building blocks of physical habitat suitability and diversity. Few studies have assessed and investigated the physical characteristics of non-perennial rivers, and this knowledge gap provided the opportunity to examine and explain the associations between fluvial style, and the characteristics and distribution of geomorphic units. In this research, a procedure to observe and measure the characteristics of morphologic features was developed and applied. The approach was based on identifying and describing the morphometric characteristics of channel and floodplain features identified by aerial image analysis and field survey.